Microwaveable beverage preparers are described in U.S. Pat. Nos. 4,303,196, issued Dec. 1, 1981; 4,104,957, issued Aug. 8, 1978; 4,132,239, issued Jan. 2, 1979; 4,158,464, issued June 19, 1979; 4,381,696, issued May 3, 1983; 4,642,443, issued Feb. 10, 1987; 4,721,835, issued Jan. 26, 1988; 4,756,915, issued July 12, 1988; 4,795,873, issued Jan. 2, 1989; 4,867,880, issued Sept. 19, 1989; and 4,908,222, issued Mar. 13, 1990.
The microwaveable coffee maker disclosed in U.S. Pat. No. 4,303,196, includes a receptacle unit for brewed coffee, a filter unit for passing water through coffee grinds, a reservoir unit for containing the water, and a mechanical valve for transferring the water from the reservoir unit to the filter unit. One problem with this type of microwaveable coffee maker is that the mechanical valve wears out over a period of time causing a break down.
The brewing apparatus and method disclosed in U.S. Pat. No. 4,908,222 discloses and claims a pressurized system with a pressure overflow means. This system does not resolve the problem of scorching or roasting of the ground coffee that occurs before the vapor pressure is built up in the reservoir sufficiently to force the heated water to overflow into the filter chamber. Additionally, because the process and apparatus disclosed is U.S. Pat. No. 4,908,222 is a pressurized system it is necessary to apply microwave energy throughout the entire process. If the microwave energy is discontinued during the process, the water flow will not continue. This excess of energy can cause the coffee to have an overcooked flavor. U.S. Pat. No. 4,908,222 does not disclose or claim a vented siphon system using hydraulic head as shown in the present invention. Further, it is necessary in U.S. Pat. No. 4,908,222 to have a quantity of unprepared liquid in the receptacle (38) prior to beginning the heating process. This unprepared liquid does not at any time contact the ground coffee and is therefore, not brewed. By contrast, in the present invention all of the liquid is initially in the fluid reservoir and passes through the filter unit containing the ground coffee.
In general, microwaveable coffee makers in the past have had a problem with roasting or scorching of the ground coffee before that material was contacted by heated water. This caused a burned taste in the prepared beverages which was unacceptable to the coffee drinkers. As described above, U.S. Pat. No. 4,908,222 does nothing to resolve this problem.